[Intel-gfx] [PATCH] drm/i915: Show number of objects without client

[Chris Wilson]

Quoting Mika Kuoppala (2018-04-19 15:16:16)
> Output the number of objects not tied to a client
> or to a vma. This amount should be quite small and
> on oom issues we can rule out significant bo leaks
> quickly by inspecting these values. Note that we are not
> fully accurate due to how we take and release the locks
> during transversal of related lists.
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Eero Tamminen <eero.t.tamminen at intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index e0274f41bc76..b1cbecfca716 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -354,8 +354,8 @@ static int per_file_stats(int id, void *ptr, void *data)
>                            stats.unbound); \
>  } while (0)
>  
> -static void print_batch_pool_stats(struct seq_file *m,
> -                                  struct drm_i915_private *dev_priv)
> +static unsigned int print_batch_pool_stats(struct seq_file *m,
> +                                          struct drm_i915_private *dev_priv)
>  {
>         struct drm_i915_gem_object *obj;
>         struct file_stats stats;
> @@ -375,6 +375,7 @@ static void print_batch_pool_stats(struct seq_file *m,
>         }
>  
>         print_file_stats(m, "[k]batch pool", stats);
> +       return stats.count;
>  }
>  
>  static int per_file_ctx_stats(int id, void *ptr, void *data)
> @@ -392,8 +393,8 @@ static int per_file_ctx_stats(int id, void *ptr, void *data)
>         return 0;
>  }
>  
> -static void print_context_stats(struct seq_file *m,
> -                               struct drm_i915_private *dev_priv)
> +static unsigned int print_context_stats(struct seq_file *m,
> +                                       struct drm_i915_private *dev_priv)
>  {
>         struct drm_device *dev = &dev_priv->drm;
>         struct file_stats stats;
> @@ -412,6 +413,7 @@ static void print_context_stats(struct seq_file *m,
>         mutex_unlock(&dev->struct_mutex);
>  
>         print_file_stats(m, "[k]contexts", stats);
> +       return stats.count;
>  }
>  
>  static int i915_gem_object_info(struct seq_file *m, void *data)
> @@ -422,7 +424,7 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>         u32 count, mapped_count, purgeable_count, dpy_count, huge_count;
>         u64 size, mapped_size, purgeable_size, dpy_size, huge_size;
>         struct drm_i915_gem_object *obj;
> -       unsigned int page_sizes = 0;
> +       unsigned int page_sizes = 0, client_count = 0, vma_count = 0;
>         struct drm_file *file;
>         char buf[80];
>         int ret;
> @@ -462,6 +464,7 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>                 }
>         }
>         seq_printf(m, "%u unbound objects, %llu bytes\n", count, size);
> +       vma_count += count;
>  
>         size = count = dpy_size = dpy_count = 0;
>         list_for_each_entry(obj, &dev_priv->mm.bound_list, mm.link) {
> @@ -490,6 +493,7 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>                 }
>         }
>         spin_unlock(&dev_priv->mm.obj_lock);
> +       vma_count += count;
>  
>         seq_printf(m, "%u bound objects, %llu bytes\n",
>                    count, size);
> @@ -511,11 +515,11 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>                                         buf, sizeof(buf)));
>  
>         seq_putc(m, '\n');
> -       print_batch_pool_stats(m, dev_priv);
> +       client_count += print_batch_pool_stats(m, dev_priv);
>         mutex_unlock(&dev->struct_mutex);
>  
>         mutex_lock(&dev->filelist_mutex);
> -       print_context_stats(m, dev_priv);
> +       client_count += print_context_stats(m, dev_priv);
>         list_for_each_entry_reverse(file, &dev->filelist, lhead) {
>                 struct file_stats stats;
>                 struct drm_i915_file_private *file_priv = file->driver_priv;
> @@ -543,12 +547,18 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>                                 request->ctx->pid : file->pid,
>                                 PIDTYPE_PID);
>                 print_file_stats(m, task ? task->comm : "<unknown>", stats);
> +               client_count += stats.count;
>                 rcu_read_unlock();
>  
>                 mutex_unlock(&dev->struct_mutex);
>         }
>         mutex_unlock(&dev->filelist_mutex);
>  
> +       seq_printf(m, "\n%d objects without vma\n",
> +                  dev_priv->mm.object_count - vma_count);

What does "without vma" mean? Instantiated but never used on the gpu, a
very small subset of unbound. I'm not sure if it has value and worry
that "without vma" is unclear internal language.

"%d unused objects (without any attached vma)" I think works better.

> +       seq_printf(m, "%d objects without client\n",
> +                  dev_priv->mm.object_count - client_count);

What does "without client" mean? What are you going to do when it is
negative (as computed it can legitimately be negative).
-Chris